Date: Sat, 28 Feb 1998 23:24:30 +0000 (GMT) From: Terry Lambert <tlambert@primenet.com> To: sbabkin@dcn.att.com Cc: shimon@simon-shapiro.org, wilko@yedi.iaf.nl, grog@lemis.com, jdn@acp.qiv.com, blkirk@float.eli.net, hackers@FreeBSD.ORG Subject: Re: SCSI Bus redundancy... Message-ID: <199802282324.QAA10147@usr08.primenet.com> In-Reply-To: <C50B6FBA632FD111AF0F0000C0AD71EE4132C6@dcn71.dcn.att.com> from "sbabkin@dcn.att.com" at Feb 28, 98 01:10:44 pm
next in thread | previous in thread | raw e-mail | index | archive | help
> > > I think Julian's SLICE code has something in that direction. DPT > > > supports INCREASING the size of a RAID-5 array by adding drives. > > > > How can that work? > > Something like > - read N RAID blocks from K disks > - compute new checksum for K+1 disks and write as less number > of RAID blocks but each one of bigger size (K+1/K times) > - add empty blocks at the end of RAID in the added space > > What am I wondering is why nobody did that before ? It's so boring > to rebuild the whole RAID if all you want is to add or remove a disk. You would have to remember to grab the blocks to be relocated with the same O(n) randomness as their allocation. 8-). This is exactly analogous to the FFS extension problem discussed in another thread. Why hasn't it been done? Maybe too many programmers and too few computer scientists? 8-). It's a math problem... ;-). Terry Lambert terry@lambert.org --- Any opinions in this posting are my own and not those of my present or previous employers. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?199802282324.QAA10147>